1. Field of the Invention
The present invention relates to an ink-jet head used in an ink-jet recording apparatus for discharging ink to print on a recording medium.
2. Description of the Related Art
JP-A-9-314836 (FIG. 1, FIG. 2) discloses an ink-jet head in which ink is distributed from a common ink chamber to each of plural pressure chambers, that is, pressure generation chambers arranged in one direction. In such an ink-jet head, an actuator unit including a piezoelectric diaphragm is bonded to a flow path unit in which a common ink chamber and nozzles are formed. When pressure is applied to ink in an arbitrary pressure chamber selected from the plural pressure chambers by the piezoelectric diaphragm, the ink is discharged from the nozzle connected to the pressure chamber. In a portion sandwiched between the pressure chamber and the common ink chamber in the flow path unit, there is provided a recess for suppressing crosstalk in which a vibration generated in a pressure chamber is transmitted to the common ink chamber to induce a pressure change in the other pressure chamber. In the ink-jet head 1 disclosed in JP-A-9-314836, all the pressure chambers are opposite to the common ink chamber, and any pressure chambers have the same positional relation with respect to the common ink chamber. Besides, the shapes of the recesses are the same for all the pressure chambers.
In recent years, in order to improve printing resolution and printing speed, an attempt has been made to arrange pressure chambers in a matrix form along a plane, that is, two-dimensionally in two directions. In this case, since it is necessary to arrange nozzles so that ink is discharged in a direction vertical to the plane on which the pressure chambers are arranged, a common ink chamber can not be provided so as to be opposite to all the pressure chambers. Accordingly, two kinds of pressure chambers are inevitably produced, that is, some pressure chambers are opposite to the common ink chamber and others are not opposite to the common ink chamber. In the two kinds of pressure chambers, each of the pressure chambers opposite to the common ink chamber has a relatively large compliance (reciprocal of rigidity) at the time of an ink discharge operation, however, each of the pressure chambers not opposite to the common ink chamber has a relatively small compliance at the time of the ink discharge operation. The difference in compliance as stated above emerges as a difference in ink discharge speed and causes degradation in picture quality.